Method of processing rubber thread



13, 1940- M B. H. FOSTER ET AL 2,211,324

METHOD OF PROCESSING RUBBER THREAD Filed Aug. 19, 1958 7 INVENTORS BOflTM ZZL f7. FOSTf/f S A v ATTORNEYS Patented Aug. 13, 1940 METHOD OF PROOESSING RUBBER THREAD Boutwell H. Foster, Maplewood, N. J., and Kenneth J. "Rupprecht, Barrington, R. 1., assignors, by mesne assignments, to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application August 19, 1938, Serial No. 225,712

4 Claims.

This invention relates to the method of an apparatus for processing or twisting bare rubber thread.

In the Foster Patent No. 2,024,156, granted December 17, 1935, there is described and claimed an elastic yarn and method of making the same. The elastic yarn of this patent comprises a rubber core twisted in one direction and having applied thereto a fibrous cover helically wound about the twisted core in the opposite direction to produce a balanced elastic yarn.' In accordance with the disclosures of said patent, the rubber core is twisted by a separate and independent operation before the cover is applied thereto.

The present invention relates primarily to a method of and apparatus for imparting the proper amount of twist to this rubber core preparatory to applying the cover thereto in accordance with said patent.

Various types of twisting frames have been provided heretofore for twisting textile yarns such as cotton silk, rayon and the like, but such 'prior constructions are not suited for imparting the desired twist to a bare rubber thread, because of the inherent properties of rubber to stretch several hundred per cent. when under tension and to contract to its original length when relaxed.

Accordingly, it becomes necessary to modify the conventional form of twisting machines as heretofore constructed, in order to impart to a rubber thread a pre-determined number of twists per inch under uniform and controlled tension.

A primary feature of the present invention therefore resides in a method of an apparatus for imparting to a bare rubber thread a pre-determined number of twists per inch in accordance with the requirements of the different size threads to be twisted and their stretch characteristics and other properties; it being extremely importantthat the twist imparted to the rubber thread be uniform throughout the same spool and from one spool to another, so as to make as nearly uniform elastic yarn as possible, particularly as to balance and elongation which are important factors in elastic yarns that are to be woven or knitted.

The present invention contemplates that the rubber thread will be twisted while it is being delivered under controlled tension from a let-off package to a take-up package, and in accordance with one embodiment of the invention the thread is twisted as itleaves the let-off package, while in a second form of the invention, the thread is twisted as it is wound upon the take-up package.

When the thread is twisted as it leaves the letoff package, it is highly important, if this operation is to be performed at high speed, that the rubber thread be previously wound upon the package under high tension, and preferably under approximately the highest tension that can be used without injury or breaking the threadso as to form a package which will not deform or ba11oon" when rotated at high speed.

One important feature of the present invention therefore resides in the step of winding the rubber thread upon its package under suflicient tension to prevent it from further stretching and thereby permit deformation of the package by centrifugal force as it is rotated at high speed.

If it is desired to make a balanced elastic yarn as contemplated by said patent then it is important that the amount of twist imparted to each inch of the rubber thread forming the core be accurately and uniformly controlled. Furthermore, it is found that the tension of the rubber thread must be accurately controlled during the twisting operation if the number of twists per inch are to be accurately controlled. For one size rubber thread we may want to vary the twist through a large range, depending upon the type of elastic yarn construction desired and degree of elongation required. These will all vary for different size cores. A high kick elastic yarn requires a high twist rubber core but this may vary with the elongation or stretch required.

Therefore another important feature of the present invention resides in rotating means located between the let-off and take-up packages and operable to accurately control the tension of the thread and twists per inch imparted to the thread by the twisting apparatus.

The present invention may be employed to process rubber thread of various sizes but it is particularly well adapted for use in imparting the desired amount of twist to finerubber threads having a diameter of of an inch or less. It may be necesary to twist these very fine threads as must as 100 turns to the inch or more, because in the subsequent operation of spinning the textile cover about this rubber core, as much as 50% of this twist may be removed.

Other features of the invention and novel combination of parts in addition to the above will be hereinafter described in connection with the accompanying drawing which illustrates good practical forms thereof.

In the drawing: 4

Fig. 1 is a more or less diagrammatic perspective view of mechanism for winding the rubber thread upon a spool under high tension;

Fig. 2 is a side elevation of one form of mechanism for twisting the rubber core; and

Fig. 3 is a side elevation of a modified type of mechanism for twisting the rubber core.

The mechanism illustrated in Fig. 1 is adapted to Wind the rubber thread under high tension upon a take-up spool to thereby provide a package that will not deform when later revolved at high speed upon the rotating spindle of the twisting mechanism of Fig. 2.

In Fig. l,'the spool I0 is a let-off package having the rubber thread R wound thereupon, and the spool II is the take-up package upon which the thread R is wound under high tension so that when this spool is later transferred to the twistingmechanism of Fig. 2 and rotated at high speed, the rubber will not stretch sufficiently to permit the package to .deform or balloon under the centrifugal force. To this end it may be desirable to wind the rubber upon the spool H under a stretch of 600% or more.

The tension, under which the thread R is wound upon the spool H is accurately controlled in accordance with the present invention by controlling the speed of the peripheral rotation of the let-off package Ill and the take-up package ll. This is accomplished in the embodiment of the invention illustrated by providing the roll l2, which may be a cork covered roll, for controlling the peripheral speed of rotation of the let-off package iii and by providing a similar roll is for driving the take-up ,package if at the desired speed.

It is important that means be provided whereby one of these spools l0, ll may be operated at various different speeds relative to the other to thereby increase or decrease the tension at which the rubber R is wound upon the take-up spool.

In the construction shown the speeds at which the rolls i2 and 83 are driven are controlled from the power shaft M which is shown as driven by the belt 15 and cooperating pulley. This shaft i l, by means of the sprockets l6 and I7 and chain l8, drives a second shaft i9 having rigidly secured thereupon the roll i2. The let-off spool it! is supported by links or the like, not shown, for swinging movement towards and from its driving roll 52, the arrangement being such that the rubber thread wound upon this spool is yieldingly forced against the surface of the roll i2 with sufficient pressure to prevent slippage therebetween, so that the peripheral speed at which this package is rotated will correspond to the speed of the roll 52. In this manner, the speed at which the thread R is unwound from the spool if] is accurately controlled.

The take-up package i i is likewise supported by means, not shown, for swinging movement towards and from the roll l3 and is yieldingly pressed against the surface of this roll with suincient force to prevent slippage therebetween. In

this manner, the take-up spool ii is driven at a constant peripheral speed irrespective of the size of the package. It will therefore be seen that by rotating the take-up package H at the proper excess speed over that of the let-off spool ID, the thread R will be wound upon the spool i I under the desired tension or elongation. The traverse bar 20 having the guide eye 2| serves to wind the rubber thread R evenly upon the spool I l,

The means shown for driving the roll 13 at the desired increase in speed over that at which the roll 12 is rotated consists of a gear 22rigidly secured to the power shaft l4 and havin meshed therewith the idler gear 23 which is supported by the links 24- for swinging movement about the power shaft M. The roll I3 is rigidly secured to an operating shaft 25 which is driven at the desired speed by a change gear 26 secured thereto and adapted to be driven from the gear 22 by the idler 23.

It will be seen that only one unit for winding a rubber thread R. upon the take-up spool under the desired tension is illustrated in Fig. 1, but it will be understood that a large number of these winding units may be provided side by side upon a supporting frame so that a number of rubber threads may be wound simultaneously on their respective spools.

Now turning our attention to the twisting mechanism of Fig. 2, which may be regarded as an up-twister, there is provided a spool supporting spindle 27 adapted to be rotated at high speed by any suitable driving means .such as the belt 28 and pulley 29. This spindle, it will be noted, has mounted thereupon a spool II, which is one of the spools having the rubber R wound thereupon under high tension by the apparatus of Fig. 1. The rubber thread R is withdrawn axially from the spool i i as the latter is rotated and passes upwardly through the pigtail or guide 30 to thereby twist this thread. The ballooning action of this thread as it leaves the rapidly rotating spool serves to throw the thread outward sufficiently to clear the spool head. The thread is then wound upon the take-up spool or package 3i which is driven at the desired peripheral speed by a roll 82 similar to the manner in which the take-up spool H is driven in Fig. 1; that is, the spool 35 is mounted for swinging movement towards and from the driving roll 32 and is held against this roll with sufficient force to prevent slippage therebetween.

The amount of twist which is to be imparted to a rubber thread will vary with the size of thread being twisted and also with the stretch characteristics and other properties that are to be imparted to the elastic yarn in which this rubber thread is to be used as a core. For example, if the same size rubber thread is employed in different elastic yarns, one type of twist will be, required for a short stretch yarn and another for a long stretch yarn, and the amount of twist required will also vary depending whether the elastic yarn has an easy or strong kick or contractive force. It therefore becomes important to provide means for accurately controlling the number of turns or twists per inch imparted to the particular rubber thread being twisted.

Therefore one important feature of the present invention resides in rotating means interposed between the let-off package 5 i and take-up package 3! and adapted to control the speed at which the rubber thread R is fed forward at this particular point to thereby control the tension of the rubber thread. In the construction shown, this intermediate means comprises the nip rolls 33 which serve to control the tension and amount of twist imparted to the rubber thread through out that portion of the thread extending from the let-off package H to the nip of these rolls, and these nip rolls serve also to control the tension of that portion of the rubber thread extending from the nip of these rolls to the take-up package 3i.

It is found that the amount of twist being imparted to the rubber thread R by the mechanism of Fig. 2 may be controlled accurately by driving the nip rolls 33 at the proper speed relative to the speed of rotation of the twisting spindle 21 and the take-up spool 3i. Change speed driving mechanism is therefore shown for operating these nip rolls and the spool driving roll 32. This means in the construction shown comprises the driving belt 34 which is operated by means, not shown, at any one of a number of diiferent speeds. This belt drives a pulley 35 mounted upon a shaft 36 upon which shaft is rigidly secured a gear 31 adapted to mesh with and drive a gear 38 which operates one of the nip rolls 33. This gear '31 also drives an idler gear 39 which in turn drives the change gear 40 that is secured to the shaft 4| which supports and operates the roll 32.

It will be seen that as a result of the mechanism just described, the nip rolls 33 and take-up spool-3i may be operated at various speeds relative to the speed of rotation of the twisting spindle 21. Since the speed at which the spool 3| is rotated in Fig. 2 to wind the rubber thread thereupon, orlater unwind the thread therefrom,

will in all probability be much less than that at which the spool II is rotated by the spindle 27, there is no need of winding this thread tightly on the spool 3| to prevent ballooning. Therefore the thread R as wound upon the spool" 3i may have from a 100 to a 300% stretch.

We will now describe the twisting mechanism illustrated in Fig. 3 which may be termed a down-twister. In this construction the rubber thread R to be twisted is supplied by the let-01f spool 42, which may be a spool similar to the spool II, but the rubber thread is preferably wound upon this spool 42 under considerable less tension than it is wound upon the spool ll. As the rubber thread is unwound from the spool 42, it passes downwardly between the nip rolls 43, and then to the pigtail or guide 44. From this pigtail, it passes downwardly to the ring 46 provided with a traveler 46 adapted to guide the thread R onto the take-up spool 41 which is mounted upon and is rotated by the twister spindle 48. This spindle may be driven by a belt 43 in the same manner that the twister spindle 21 of Fig. 2 is driven. The ring 45 is traversed in a well-known mariner axially of the spool 41- to wind the thread evenly thereupon, and the desired twist is imparted to that portion of the rubber R which extends between the rotating spool 41 and nip rolls 43 by the rapid rotation of this spool and relatively slow feed of the thread by the nip rolls.

In this mechanism, as in the'eonstmc'tion of Fig. 2, it is important to provide means whereby the nip rolls 43 and let-oi! spool 42 may be rotated at various diflerent speeds relative to the speed of rotation of the twister spindler 43. The means shown in Fig. 3 for operating the nip rolls 43 and spool 42 are substantially the same as that illustrated in Fig. 2, and comprise the power belt 50 adapted to be operated at different speeds to drive the gear 5! that meshes with and drives a gear 32 attached to one of the nip rolls 43. The gear II also drives the idler 33 which in turn drives the change gear 54. This gear I4 serves to operate a roll that engages the periphery of the let-off package 42 to rotate the same at the desired peripheral speed.

j It will be understood that while only one twistingunitisshowninIflgJandinFigJJhatin each case a twisting frame may be employed provided with a number of these units to thereby twist simultaneously a large number of threads R either of the same size or of difierent sizes.

The present invention was developed primarily to impart a desired amount of twist to a fine bare rubber thread, which thread, due to its fineness, is difllcult to handle without stretching the same. Therefore the problem of imparting just the" right amount of twist to a rubber thread which varies substantially in length with slight variation in the tension to which it is subjected, was not an easy one. The solution of this problem resulted largely from the use of the intermediate nip. rolls or the like whereby the tension of this fine rubber thread can be accurately controlled at an intermediate point between the letofi and take-up package during the twisting operation.

Having thus described our invention what we claim and desire to protect by Letter Patent is:

1. The method of twisting and packaging a bare rubberthread, which consists in winding the rubber thread upon a spool in a highly stretched condition to prevent its ballooning when rotated rapidly, rotating the spool at high speed, pulling the thread axially from the rotating spool at a uniform speed to thereby twist the thread a predetermined amount, advancing the twisted thread in the same general direction to a take-up package and winding it thereupon under much less tension and stretch.

2. The method of twisting and packaging a bare rubber thread, which consists in winding the rubber thread upon a spool under at least 600 elongation to form a package that will not deform when rotated at high speed, rotating the spool at high speed, pulling the thread axially from the rotating spool at a uniform speed to twist the thread a predetermined amount, and advancing the twisted thread in the same general direction to a take-up package and winding it thereupon under less than 300% elongation.

3. The method of twisting and packaging a 'bare rubber thread, which consists in winding the rubber thread upon a spool in a highly stretched condition to prevent it from deforming when rotated rapidly, rotating the spool at ,high speed, pulling the thread upwardly therefrom in an axial direction from the rotating spool at a uniform speed to thereby twist the thread a predetermined amount, and advancing the twisted thread in the same general upward direction to a takeup package and winding it thereupon under much less tension and==stretch.

4. The method of twisting and packaging a bare rubber thread, which consists in winding the rubber thread upon a spool in a sufflciently stretched condition to prevent it from deforming upon this spool when rotated rapidly, rotating the spool at high speed, pulling the thread off from an end of the rotating spool at a uniform speed that is correlated to the speed of spool rotation to thereby twist the thread a predetermined amount, and advancing the twisted thread under controlled tension from the point at which it is being pulled directly to a take-up package and winding it thereupon under less tension and stretch.

- BOUTWELL H. FOSTER.

ENNETHJRUPPRECHT. 

